Radio continuum of galaxies with H${}_2$O megamaser disks: 33 GHz VLA data

Abstract

We investigate the nuclear environment of galaxies with observed 22 GHz water megamaser in their subparsec edge-on accretion disks, using 33 GHz (9mm) radio continuum data from VLA, with a resolution of ~ 0.2-0.5 arcsecs, and relate the maser and host galaxy properties to those of its radio continuum emission. Eighty-seven percent (21 out of 24) galaxies in our sample show 33 GHz radio continuum emission at levels of 4.5-240 $\sigma$. Five sources show extended emission, including one source with two main components and one with three main components. The remaining detected 16 sources exhibit compact cores within the sensitivity limits. Little evidence is found for extended jets (>300 pc) in most sources. Either they do not exist, or our chosen frequency of 33 GHz is too high for a detection of these supposedly steep spectrum features. In only one source among those with known maser disk orientation, NGC4388, we found an extended jet-like feature that appears to be oriented perpendicular to the water megamaser disk. Smaller 100-300 pc sized jets might also be present, as is suggested by the beam-deconvolved morphology of our sources. Whenever possible, central positions with accuracies of 20-280 mas are provided. A correlation analysis shows that the 33 GHz luminosity weakly correlates with the infrared luminosity. The 33 GHz luminosity is anticorrelated with the circular velocity of the galaxy. The black hole masses show stronger correlations with water maser luminosity than with 1.4 GHz, 33 GHz, or hard X-ray luminosities. Furthermore, the inner radii of the disks show stronger correlations with 1.4 GHz, 33 GHz, and hard X-ray luminosities than their outer radii, suggesting that the outer radii may be affected by disk warping, star formation, or peculiar density distributions.

18 pages, 10 figures, Accepted for publication in A&A

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• The Megamaser Cosmology Project. XI. A geometric distance to CGCG 074-064
• Accretion disk versus jet orientation in H${}_2$O megamaser galaxies
• Water megamaser emission in hard X-ray selected AGN
• Estimating the mass-to-distance ratio for a set of megamaser AGN black holes by employing a general relativistic method
• IC 485:a new candidate disk-maser galaxy at $\sim$100 Mpc distance. Milliarcsecond resolution study of the galaxy nucleus and of the $H_{2}O$ megamaser